Rory McIlroy and Patrick Reed were threatening to set up a repeat of their Ryder Cup showdown as damp conditions failed to prevent fireworks in the third round of the Masters.
McIlroy began the day five shots off the lead held by Reed, but birdied the third and fourth and then almost holed his tee shot on the par-three sixth.
And the best was yet to come as the former world number one chipped in for an eagle on the par-five eighth in pursuit of the win he needs to complete the career grand slam.
That briefly gave McIlroy a share of the lead, only for Reed to respond with a hat-trick of birdies from the eighth - the fifth time this week he has compiled such a scoring burst.
A bogey on the 12th cut Reed's lead to two, but he responded with an eagle on the 13th - where McIlroy had to save par from deep in the Azaleas left of the green - to move four shots clear.
Spain's Jon Rahm had set the clubhouse target on eight under after a flawless 65, the lowest score of the week.
European number one Tommy Fleetwood, who played alongside Tiger Woods in the first two rounds, was two shots further back after a superb 66 which included six birdies, including five in a row from the 12th.
"The course was playing a lot easier," said Fleetwood, whose only bogey came from a three-putt on the 18th. "The greens were pretty soft and the wind was not really blowing very hard. If there was ever a day to shoot a good round here, this was it.
"It's a bit weird walking off disappointed with a 66. I played great on the front nine without holing any putts and after misjudging a short one on 11 it was nice to getting something going after that.
"Today was just about doing the best I could, my first weekend at Augusta and I wasn't thinking about the lead at all. I got a lot closer and it was nice to play last few holes with a bit of adrenaline, but there's nothing you can do about the other guys."
McIlroy had enjoyed a lucky bounce on the first when his pulled drive hit a tree and bounced down into the first cut of rough, from where he missed the green and had to get up and down for par.
Another wayward drive on the second meant McIlroy failed to take advantage of the reachable par five, but the 28-year-old's much-maligned putting came to the rescue when he holed treacherous putts from 20 feet on both the third and fourth.
McIlroy could even have birdied the fifth in remarkable fashion after his second shot hit the lip of a fairway bunker but somehow had enough top spin to reach the green, although he was unable to convert from 12 feet.
A stunning tee shot on the sixth left the Northern Irishman with a tap-in for birdie and the putter was not even needed on the eighth as his chip from right of the green - which was travelling at some speed - hit the pin and dropped in for an eagle.
The latest from Augusta saw McIlroy lie three shots behind Reed.
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